1. Field of the Invention
The present invention is generally related to a throttle body support structure for an internal combustion engine and, more particularly, to an elastomeric support member that supports a throttle body of an internal combustion engine relative to an air intake manifold of the engine without direct contact between the throttle body structure and the air intake manifold.
2. Description of the Prior Art
Internal combustion engines inherently create vibration due to the internal moving components, such as pistons, connecting rods, and crankshafts. It is important that certain components, such as electronic devices and wiring connections, be protected from potential damage that can occur if those relatively delicate components are subjected to significant vibration over extended periods of time.
U.S. Pat. No. 5,813,886, which issued to Shomura on Sep. 29, 1998, describes a structure for mounting a control sensor in an outboard motor. The structure permits a reduced number of components for attaching control sensors, a high degree of freedom for laying out the parts constituting the engine, efficient wiring, further improved vibration insulating properties, and use of a throttle body employed for an engine of equipment other than an outboard motor. A discrete sensor mounting holder, as a single unit, which is composed of a vibration proof member and which holds an intake air temperature detecting sensor, and an atmospheric pressure detecting sensor, respectively, is fixed to an engine of the outboard motor, the engine being provided with a fuel injecting unit and the intake air temperature detecting sensor and the atmospheric pressure detecting sensor for controlling the fuel injecting unit.
U.S. Pat. No. 5,769,045, which issued to Edwards et al on Jun. 23, 1998, describes a modular air induction system with an isolated throttle body. The air induction system for an internal combustion engine features a throttle body and air cleaner assembly vibration-isolated from the engine by a resilient air transmitting zip tube interconnecting the throttle body with the engine air intake manifold. The zip tube flexes to isolate the throttle body from the engine vibrations and oscillations thereby eliminating a cause of throttle body fractures or looseness from its mounting. Furthermore, with such oscillation, the throttle body can be readily formed from plastics and perform long service life. With the throttle body isolated, engine generated throttle pedal vibration is eliminated. Additionally with the remote location, throttle body and throttle plate coking and icing from recirculating exhaust gases is obviated. The throttle body and air cleaner assembly is supplied as a unit to augment vehicle assembly.
U.S. Pat. No. 5,229,671, which issued to Neidhard et al on Jul. 20, 1993, describes an electromagnetic rotary actuator. In a rotary actuator with rotary slide valve for controlling a throttle cross-section, the sealing of the pneumatic and of the electrical part is improved. The shaft is supported twofold, both on this side and on the other side of the rotary slide valve. Both roller bearings are located in a one-piece housing. As a result, the tolerance-related width of the air gap between rotary slide valve and control opening is reduced, on the one hand, and, on the other hand, an isolating seal between the parts and is formed by the bearing. The rotary actuator is particularly suitable as idle-speed rotary actuator for internal combustion engines.
U.S. Pat. No. 4,894,638, which issued to Flierl et al on Jan. 16, 1990, describes a potentiometer having vibration damping means. The potentiometer for attachment to objects undergoing strong vibrations, such as the engine block of an internal combustion engine, has an outer housing which is secured to the object and an inner housing which is largely positioned inside the outer housing. The two housings are connected by at least one springy damping member, such as an O-ring made of rubber and, at the same time, they are largely uncoupled with respect to vibrations.
U.S. Pat. No. 4,615,398, which issued to Nagashima on Oct. 7, 1986, describes a throttle cushion. The throttle cushion of a portable power-driven machine has a sleeve-like elastic cushioning member fitted on the portion of a trigger engageable with a throttle valve actuating rod.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
As can be seen in the patents cited above, it is well known to those skilled in the art of internal combustion engines that certain components benefit significantly from being isolated from vibrations caused by the operation of the internal combustion engine. Some vibration isolation techniques are intended to improve the comfort of the machine operator while others are intended to protect either mechanical or electrical elements of the structure.
In certain types of internal combustion engines, electronic components are mounted directly to the throttle body of the engine for support. As an example, certain throttle body designs incorporate a motor which moves the throttle plate about its central axis in response to commands received from an engine control unit (ECU). The rotation of the throttle plate can be monitored by a rotational position sensor, such as a potentiometer or a Hall effect device. Furthermore, the relationship between the motor and the throttle plate axis typically includes a combination of gears and a return spring. The electrical components associated with the motor and potentiometer are typically connected in electrical communication with an engine control unit that is mounted at a location on the engine which is remote from the throttle body. This, in turn, requires electrical connectors for plugs to provide this electrical connection. All of these components are subject to damage or degradation if they are not protected to some degree from the vibration caused by the internal combustion engine. It would therefore be significantly beneficial if a throttle body of an engine could be mounted in such a way that it is isolated from at least some of the vibrations caused by the engine.
A marine propulsion apparatus, made in accordance with the present invention comprises an internal combustion engine having an air intake chamber, or manifold and a throttle body structure having a throttle plate supported for rotation within a cavity of the throttle body structure. It also comprises an elastomeric support member attached to the air intake chamber and to the throttle body structure to support the throttle body structure in non-contact association with the air intake chamber.
It also comprises an adapter plate attached between the internal combustion engine and the elastomeric support member. The elastomeric support member can be attached to the adapter plate by a ring which surrounds portions of the adapter plate and portions of the elastomeric support member.
The preferred embodiment of the present invention can further comprise an isolator plate attached to the throttle body structure for the purpose of captivating the portion of the elastomeric support member between the isolator plate and the throttle body structure. The elastomeric support member can be provided with a sealing lip which extends between the isolator plate and the throttle body structure for, the purpose of preventing air from flowing into the air intake chamber from between the isolator plate and the throttle body structure. The cavity of the throttle body structure is generally cylindrical and the sealing lip can be disposed in a plane which is generally perpendicular to a central axis of the generally cylindrical cavity.
The present invention can further comprise a sealing protrusion extending from the elastomeric support structure in a direction toward the throttle body structure and into a generally circular groove formed in the throttle body structure. The cavity of the throttle body structure is generally cylindrical. The sealing protrusion is generally cylindrical and coaxial with the cavity. The sealing protrusion is compressible within the groove in response to the isolator plate being rigidly attached to the throttle body structure.
In a preferred embodiment of the present invention, the internal combustion engine comprises a crankshaft which is supported for rotation about a generally vertical axis. The most common application of the internal combustion engine in this arrangement is in conjunction with an outboard motor. The present invention can further comprise a motor attached to the throttle body structure. The motor is operatively attached to a shaft of the throttle plate in order to rotate the throttle plate within the cavity of the throttle body structure. A rotational position sensor, such as a potentiometer or Hall effect device, can be attached to the throttle body structure and operatively attached to the shaft of the throttle plate in order to determine a rotational position of the shaft.